Ceramic powder composition, ceramic material, and laminated ceramic condenser comprised thereof

ABSTRACT

A ceramic powder composition, ceramic material, and laminated ceramic condenser comprised thereof. The composition includes ceramic powders comprising (Sr x Ca 1-x )Ti y Zr 1-y O 3 , and a sintering aid, wherein x is between 0 and 1, and y is between 0 and 0.1. The sintering aid is M a   2 O, M b O, M c   2 O 3 , M d O 2 , or a combination thereof. Element M a  comprises Li, Na, K, or a combination thereof. Element M b  comprises Be, Mg, Ca, Sr, Ba, or a combination thereof. Element M c  comprises B, Al, Ga, or a combination thereof. Element M d  comprises Si, Ge, or a combination thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to ceramic compositions, and in particular toceramic powder composition utilized in passive devices.

2. Description of the Related Art

Ceramic materials with a main component of titanate are typicallyutilized as a dielectric of a conventional laminated ceramic condenser.The titanates become semiconductors due to reductive reaction thereofduring sintering thereof under neutral or reductive atmosphere. Thus,the titanates are typically sintered under an oxidized atmosphere. As aresult, it is necessary for inner electrodes of the condenser to have amelting point higher than the sintering temperature and to not oxidizeunder an oxidized atmosphere. It is thus necessary to utilize noblemetals such as Pd or Pt as the inner electrodes, substantiallyincreasing process cost of the laminated ceramic condenser.

Kojima et al. disclose a non-reductive ceramic material having a maincomponent represented by [(Ca_(x)Sr_(1-x))O]_(m)[(Ti_(y)Zr_(1-x))O₂],wherein x is between 0 and 1, y is between 0 and 0.10, and m is between0.75 and 1.04, and an auxiliary component containing 0.2-5 mol %(calculated MnO) of Mn oxide, 0.1-10 mol % (calculated as Al₂O₃) of Aloxide and 0.5-15 mol % of a component of [(Ba_(z)Ca_(1-z))O]_(v)SiO₂,wherein z is between 0 and 1, and v is between 0.5 and 4.0 in U.S. Pat.No. 6,118,648. The sintering temperature of the ceramic material doesnot exceed 1300° C., and Ni, having a melting point of 1455° C., can beutilized as inner electrodes.

With development of high-frequency components, the inner electrodesthereof require materials with low impedance such as Cu having a meltingpoint of 1085° C. Kojima et al., however, do not disclose the technologyto lower the sintering temperature below 1085° C., and thus, it isdifficult to introduce copper inner electrodes to the ceramic materialsdisclosed by Kojima et al.

BRIEF SUMMARY OF THE INVENTION

The invention provides ceramic powder compositions, ceramic materials,and laminated ceramic condensers comprised thereof, capable of sinteringat a temperature lower than the melting point of copper, enablingcopper, with lower impedance, utilizing inner electrodes of thelaminated ceramic condensers.

The invention provides a ceramic powder composition comprising about 80to about 90 weight percent of ceramic powders comprising(Sr_(x)Ca_(1-x))Ti_(y)Zr_(1-y)O₃, and about 10 to about 20 weightpercent of a sintering aid of M^(a) ₂O, M^(b)O, M^(c) ₂O₃, M^(d)O₂, or acombination thereof, wherein x is between 0 and 1, y is between 0 and0.1, element M^(a) comprises Li, Na, K, or a combination thereof,element M^(b) comprises Be, Mg, Ca, Sr, Ba, or a combination thereof,element M^(c) comprises B, Al, Ga, or a combination thereof, and elementM^(d) comprises Si, Ge, or a combination thereof.

The invention further provides a ceramic material sintered from theceramic powder composition, wherein the sintering temperature thereof isbetween 900 and 1000° C.

The invention further provides a laminated ceramic condenser comprisinga ceramic dielectric, a plurality of parallel inner electrodes, and apair of outer electrodes. The ceramic dielectric is sintered from theceramic powder composition, wherein the sintering temperature thereof isbetween 900 and 1000° C. The parallel inner electrodes extend in theceramic dielectric. The outer electrodes are exposed on the ceramicdielectric and electrically connect the inner electrodes.

Further scope of the applicability of the invention will become apparentfrom the detailed description given hereinafter. It should beunderstood, however, that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a cross-section of a laminated ceramic condenser of apreferred embodiment of the invention; and

FIG. 2 is a graphic chart showing equivalent series resistances (ESR) ofinventive and conventional laminated ceramic condensers, wherein theinventive condenser utilizes copper inner electrodes and the ceramicmaterials of example 5A of the invention, while the conventionalcondenser utilizes silver-palladium inner electrodes and conventionalceramic materials.

FIG. 3 is a graphic chart showing quality factors of inventive andconventional laminated ceramic condensers, wherein the inventivecondenser utilizes copper inner electrodes and the ceramic materials ofexample 5A of the invention, while the conventional condenser utilizessilver-palladium inner electrodes and conventional ceramic materials.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best-contemplated mode of carryingout the invention. This description is made for the purpose ofillustrating the general principles of the invention and should not betaken in a limiting sense. The scope of the invention is best determinedby reference to the appended claims.

The inventors found the sintering temperature of ceramic powderscomprising (Sr_(x)Ca_(1-x))Ti_(y)Zr_(1-y)O₃(0≦x≦1,0≦y≦0.1) can belowered to between 900 and 1000° C. when an inventive sintering aid isadded thereto. The temperature is lower than the melting point ofcopper, allowing utilization of Cu as inner electrodes of laminatedceramic condensers. The inventive sintering aid is M^(a) ₂O, M^(b)O,M^(c) ₂O₃, M^(d)O₂, or a combination thereof, wherein element M^(a)comprises Li, Na, K, or a combination thereof, element M^(b) comprisesBe, Mg, Ca, Sr, Ba, or a combination thereof, the element M^(c)comprises B, Al, Ga, or a combination thereof, and the element M^(d)comprises Si, Ge, or a combination thereof. The inventive sintering aidpreferably comprises more than 50 weight percent but less than 100weight percent of M^(d)O₂, 10 weight percent of M^(c) ₂O₃ or less, 10 to30 weight percent of M^(b)O, and 10 weight percent of M^(a) ₂O or less.

In an embodiment, the inventive sintering aid comprises a combination offour oxides selected from each of groups M^(a) ₂O, M^(b)O, M^(c) ₂O₃,and M^(d)O₂. For example, the inventive sintering aid may compriseLi₂O—BaO—Al₂O₃—SiO₂ or Li₂O—BaO—B₂O₃—SiO₂, or alternatively, Li₂O may bereplaced by Na₂O or K₂O, BaO may be replaced by BeO, MgO, CaO, or SrO,Al₂O₃ or B₂O₃ may be replaced by Ga₂O₃, and SiO₂ may be replaced byGeO₂. In an alternative embodiment, the inventive sintering aidcomprises a combination of five oxides, wherein three are selected fromeach of groups M^(a) ₂O, M^(b)O, and M^(d)O₂, and two are selected fromgroup M^(c) ₂O₃. The inventive sintering aid preferably comprisesLi₂O—BaO—B₂O₃—Al₂O₃—SiO₂, allowing lowering of the sintering temperaturebelow 950° C., or alternatively, Li₂O may be replaced by Na₂O or K₂O,BaO may be replaced by BeO, MgO, CaO, or SrO, Al₂O₃ or B₂O₃ may bereplaced by Ga₂O₃, and SiO₂ may be replaced by GeO₂. In an alternativeembodiment, the inventive sintering aid comprises a combination of sixor more oxides selected from each of groups M^(a) ₂O, M^(b)O, M^(c) ₂O₃,and M^(d)O₂ as desired.

A novel ceramic powder composition of the invention comprises ceramicpowders and a sintering aid. The ceramic powders comprise(Sr_(x)Ca_(1-x))Ti_(y)Zr_(1-y)O₃ powders, wherein x is between 0 and 1,and y is between 0 and 0.1. The sintering aid is M^(a) ₂O, M^(b)O, M^(c)₂O₃, and M^(d)O₂, or a combination thereof, wherein the element M^(a)comprises Li, Na, K, or a combination thereof, the element M^(b)comprises Be, Mg, Ca, Sr, Ba, or a combination thereof, the elementM^(c) comprises B, Al, Ga, or a combination thereof, and the elementM^(d) comprises Si, Ge, or a combination thereof. The ceramic powdercomposition may comprise any ratio of the ceramic powders and thesintering aid as desired product properties, and preferably comprisesabout 80 to about 90 weight percent of the ceramic powders and about 10to about 20 weight percent of the sintering aid. More preferably, y isbetween 0 and 0.05. The ceramic powder composition may further comprisean additive such as oxides of Mn, oxides of Mg, or a combinationthereof. The content of the additive in the ceramic powder compositionis preferably as large as 1.5 weight percent or less, and morepreferably as large as 1 weight percent or less.

In some cases, the ceramic powder composition of the invention isutilized in a laminated ceramic condenser as shown in FIG. 1. Theceramic powder composition of the invention is mixed with an organiccarrier to form slurry, followed by tape casting to form green sheets.The green sheets are then laminated with the inner electrodes, and thelaminated bodies are co-sintered at a temperature between 900 and 1000°C. The sintered green sheets become the ceramics 2 shown in FIG. 1,acting as ceramic dielectrics of the laminated ceramic condensers.

The parallel inner electrodes 3 extend in the ceramic dielectric 2, andthe terminals thereof are alternatively exposed on opposing surfaces ofthe ceramic dielectric 2. Finally, a pair of outer electrodes 4 isformed on the opposing surfaces of the ceramic dielectric 2,electrically connecting to the corresponding inner electrodes. Thus, thelaminated ceramic condenser is complete.

When sintering the ceramic powder composition of the invention, thesintering atmosphere is preferably reductive, utilizing an atmospheresuch as a mixed atmosphere of hydrogen and nitrogen, or nitrogenatmosphere. A ratio of sintered density to theoretical density of theceramic dielectric 2 is preferably between 0.9 and 1. In one embodiment,the inner electrodes comprise copper.

Several examples of the ceramic powder composition, ceramic material,and laminated ceramic condenser are listed as follows. Note that thematerials and process described in these examples are not intended tolimit the scope of the invention. Those skilled in the art willrecognize the possibility of using various materials and processes toachieve the described ceramic powder composition, ceramic material, andlaminated ceramic condenser.

The subsequent examples utilize ceramic powders comprising(Sr_(x)Ca_(1-x))Ti_(y)Zr_(1-y)O₃, wherein x is between 0 and 1, and y isbetween 0 and 0.1, and a sintering aid comprisingLi₂O—BaO—B₂O₃—Al₂O₃—SiO₂, wherein the content of SiO₂ in the sinteringaid is more than 50 weight percent, the content of B₂O₃—Al₂O₃ in thesintering aid is 10 weight percent or less, the content of BaO in thesintering aid is between 10 and 30 weight percent, and the content ofLi₂O in the sintering aid is 10 weight percent or less.

EXAMPLE 1

Approximately 95 weight percent of the ceramic powders and approximately5 weight percent of the sintering aid were passed through a 400-mesh,followed by mixing with an organic carrier such as polyvinyl alcohol(PVA) to form ceramic slurry. The ceramic slurry was then pressed underapproximately 5 kgw/cm² to form green sheets. The green sheets, dividedinto four groups, were respectively sintered under two atmospheres (airand a mixture of nitrogen and hydrogen) and at three temperatures(approximately 900° C., approximately 950° C., and approximately 1000°C.) for approximately 120 minutes. The sintering process compriseddegreasing, during which the green sheets were heated at a rate ofapproximately 1° C./min. to slowly remove the organic carrier therein,and remained at approximately 300° C. for 60 minutes to completelyremove the organic carrier, and main sintering, during which thedegreased sheets were put in furnaces under the desired atmosphere,heated to the desired sintering temperature for at most approximately200 minutes, and then remained at the desired temperature forapproximately 120 minutes, followed by air cooling to terminatesintering. Finally, the densities of the sintered sheets were measuredand compared with the theoretical density. The results are listed inTable 1. In this example, the ratios of the sintered densities of thefour groups of sintered sheets to the theoretical density were all lessthan 90%.

EXAMPLE 2

In addition to the contents of the ceramic powders and the sinteringaid, the process and measurement steps utilized here are the same asthose in Example 1. Here, the ceramic powder composition comprisesapproximately 90 weight percent of the ceramic powders and approximately10 weight percent of the sintering aid, both completely mixed by a ballmill, followed by being passed through the 400-mesh. After sintering,the densities of the sintered sheets were measured and compared with thetheoretical density. The results are listed in Table 1. In this example,the ratios of the sintered densities of the four groups of sinteredsheets to the theoretical density may be greater than 90%.

EXAMPLE 3A

In addition to the contents of the ceramic powders and the sinteringaid, the process and measurement steps utilized here are the same asthose in Example 2. Here, the ceramic powder composition comprisesapproximately 90 weight percent of the ceramic powders, approximately 9weight percent of the sintering aid, and approximately 1 weight percentof an additive comprising MnO₂. After sintering, the densities of thesintered sheets were measured and compared with the theoretical density.The results are listed in Table 1. In this example, the ratios of thesintered densities of the four groups of sintered sheets to thetheoretical density can be greater than 90%.

EXAMPLE 3B

In addition to the contents of the ceramic powders and the sinteringaid, the process and measurement steps utilized here are the same asthose in Example 2. Here, the ceramic powder composition comprisesapproximately 90 weight percent of the ceramic powders, approximately9.5 weight percent of the sintering aid, and approximately 0.5 weightpercent of an additive comprising MgO. After sintering, the densities ofthe sintered sheets were measured and compared with the theoreticaldensity. The results are listed in Table 1. In this example, the ratiosof the sintered densities of the four groups of sintered sheets to thetheoretical density can be greater than 90%.

EXAMPLE 4

In addition to the contents of the ceramic powders and the sinteringaid, the process and measurement steps utilized here are the same asthose in Example 2. Here, the ceramic powder composition comprisesapproximately 85 weight percent of the ceramic powders and approximately15 weight percent of the sintering aid. After sintering, the densitiesof the sintered sheets were measured and compared with the theoreticaldensity. The results are listed in Table 1. In this example, the ratiosof the sintered densities of the four groups of sintered sheets to thetheoretical density can be greater than 90%.

EXAMPLE 5A

In addition to the contents of the ceramic powders and the sinteringaid, the process and measurement steps utilized here are the same asthose in Example 2. Here, the ceramic powder composition comprisesapproximately 85 weight percent of the ceramic powders, approximately 14weight percent of the sintering aid, and approximately 1 weight percentof an additive comprising MnO₂. After sintering, the densities of thesintered sheets were measured and compared with the theoretical density.The results are listed in Table 1. In this example, the ratios of thesintered densities of the four groups of sintered sheets to thetheoretical density can be greater than 90%.

EXAMPLE 5B

In addition to the contents of the ceramic powders and the sinteringaid, the process and measurement steps utilized here are the same asthose in Example 2. Here, the ceramic powder composition comprisesapproximately 85 weight percent of the ceramic powders, approximately14.5 weight percent of the sintering aid, and approximately 0.5 weightpercent of an additive comprising MgO. After sintering, the densities ofthe sintered sheets were measured and compared with the theoreticaldensity. The results are listed in Table 1. In this example, the ratiosof the sintered densities of the four groups of sintered sheets to thetheoretical density can be greater than 90%.

EXAMPLE 6

In addition to the contents of the ceramic powders and the sinteringaid, the process and measurement steps utilized here are the same asthose in Example 2. Here, the ceramic powder composition comprisesapproximately 80 weight percent of the ceramic powders and approximately20 weight percent of the sintering aid. After sintering, the densitiesof the sintered sheets were measured and compared with the theoreticaldensity. The results are listed in Table 1. In this example, the ratiosof the sintered densities of the four groups of sintered sheets to thetheoretical density can be greater than 90%.

EXAMPLE 7A

In addition to the contents of the ceramic powders and the sinteringaid, the process and measurement steps utilized here are the same asthose in Example 2. Here, the ceramic powder composition comprisesapproximately 80 weight percent of the ceramic powders, approximately 19weight percent of the sintering aid, and approximately 1 weight percentof an additive comprising MnO₂. After sintering, the densities of thesintered sheets were measured and compared with the theoretical density.The results are listed in Table 1. In this example, the ratios of thesintered densities of the four groups of sintered sheets to thetheoretical density can be greater than 90%.

EXAMPLE 7B

In addition to the contents of the ceramic powders and the sinteringaid, the process and measurement step utilized here were the same asthose in Example 2. Here, the ceramic powder composition comprisesapproximately 80 weight percent of the ceramic powders, approximately19.5 weight percent of the sintering aid, and approximately 0.5 weightpercent of an additive comprising MgO. After sintering, the densities ofthe sintered sheets were measured and compared with the theoreticaldensity. The results are listed in Table 1. In this example, the ratiosof the sintered densities of the four groups of sintered sheets to thetheoretical density can be greater than 90%.

EXAMPLE 8

In addition to the contents of the ceramic powders and the sinteringaid, the process and measurement steps utilized here are the same asthose in Example 2. Here, the ceramic powder composition comprisesapproximately 80 weight percent of the ceramic powders, approximately18.5 weight percent of the sintering aid, and approximately 1.5 weightpercent of an additive, comprising approximately 1 weight percent ofMnO₂ and approximately 0.5 weight percent of an additive comprising MgO.After sintering, the densities of the sintered sheets were measured andcompared with the theoretical density.

The results are listed in Table 1. In this example, the ratios of thesintered densities of the four groups of sintered sheets to thetheoretical density can be greater than 90%. TABLE 1 density ratiosintering theoret- of theo- tempera- ical sintering retical to Exam-sintering ture density density sintering ple atmosphere ° C. (gm/cm³)(gm/cm³) (%) 1 mixture of 900 5.21 4.42 84.7 nitrogen and hydrogen 1mixture of 950 5.21 4.15 79.7 nitrogen and hydrogen 1 mixture of 10005.21 4.54 87.1 nitrogen and hydrogen 1 nitrogen 950 5.21 4.06 77.9 2mixture of 900 5.00 4.22 84.3 nitrogen and hydrogen 2 mixture of 9505.00 4.17 83.3 nitrogen and hydrogen 2 mixture of 1000 5.00 4.57 91.4nitrogen and hydrogen 2 nitrogen 950 5.00 4.07 81.3 3A mixture of 9004.98 4.25 85.2 nitrogen and hydrogen 3A mixture of 950 4.98 4.64 93.2nitrogen and hydrogen 3A mixture of 1000 4.98 4.79 96.1 nitrogen andhydrogen 3A nitrogen 950 4.98 4.52 90.7 3B mixture of 900 5.00 4.10 81.9nitrogen and hydrogen 3B mixture of 950 5.00 4.24 84.7 nitrogen andhydrogen 3B mixture of 1000 5.00 4.61 92.2 nitrogen and hydrogen 3Bnitrogen 950 5.00 4.18 83.6 4 mixture of 900 4.83 3.99 82.5 nitrogen andhydrogen 4 mixture of 950 4.83 4.23 87.4 nitrogen and hydrogen 4 mixtureof 1000 4.83 4.73 97.8 nitrogen and hydrogen 4 nitrogen 950 4.83 4.0984.6 5A mixture of 900 4.82 3.93 81.7 nitrogen and hydrogen 5A mixtureof 950 4.82 4.55 94.5 nitrogen and hydrogen 5A mixture of 1000 4.82 4.5995.4 nitrogen and hydrogen 5A nitrogen 950 4.82 4.48 93.1 5B mixture of900 4.83 4.01 83.0 nitrogen and hydrogen 5B mixture of 950 4.83 4.0684.1 nitrogen and hydrogen 5B mixture of 1000 4.83 4.47 92.4 nitrogenand hydrogen 5B nitrogen 950 4.83 3.96 81.8 6 mixture of 900 4.69 3.7980.9 nitrogen and hydrogen 6 mixture of 950 4.69 4.13 88.0 nitrogen andhydrogen 6 mixture of 1000 4.69 4.53 96.5 nitrogen and hydrogen 6nitrogen 950 4.69 4.00 85.2 7A mixture of 900 4.68 3.66 78.2 nitrogenand hydrogen 7A mixture of 950 4.68 4.51 96.5 nitrogen and hydrogen 7Amixture of 1000 4.68 4.46 95.3 nitrogen and hydrogen 7A nitrogen 9504.68 4.44 95.0 7B mixture of 900 4.69 3.73 79.6 nitrogen and hydrogen 7Bmixture of 950 4.69 4.01 85.4 nitrogen and hydrogen 7B mixture of 10004.69 4.69 100.0 nitrogen and hydrogen 7B nitrogen 950 4.69 3.94 83.9 8mixture of 900 4.69 3.89 82.9 nitrogen and hydrogen 8 mixture of 9504.69 4.32 92.1 nitrogen and hydrogen 8 mixture of 1000 4.69 4.58 97.6nitrogen and hydrogen 8 nitrogen 950 4.69 4.27 91.1

In addition to Example 1, the conditions of other examples match theceramic powder composition comprising about 80 to about 90 weightpercent of the ceramic powders and about 10 to about 20 weight percentof the sintering aid, which can be sintered at a temperature between 900and 1000° C., resulting in the ratio of sintering density to theoreticaldensity potentially as large as 0.9 or greater. Thus, inner electrodescomprising copper can be co-sintered with the inventive ceramic powdercomposition to produce the laminated ceramic condenser of the invention.

Further, the ceramic powder composition of the invention can be shapedby a conventional process such as dry pressing, cold isostatic pressing(CIP), hot isostatic pressing (HIP), or other methods to form ceramicbodies of different shapes for various usages. For example, the ceramicpowder composition of the invention can be with water and a binder suchas PVA, followed by performance of spray granulation to improve themobility of the powders. A series of processes comprising dry pressing,degreasing, and sintering is performed utilizing the resulting powdersto produce a dielectric ceramic product.

FIG. 2 is a graphic chart showing equivalent series resistances (ESR) ofan inventive and a conventional laminated ceramic condensers, and FIG. 3is a graphic chart showing quality factors (Q values) thereof, whereinthe inventive condenser utilizes copper inner electrodes and the ceramicmaterials of the example 5A of the invention, while the conventionalcondenser utilize silver-palladium inner electrodes and conventionalceramic materials. The data of FIGS. 2 and 3 shows the inventivecondenser utilizing copper inner electrodes and the ceramic materials ofthe example 5A of the invention has lower ESR and higher Q value,improving the electrical performance thereof. Furthermore, thespecification of the condensers utilized for FIGS. 2 and 3 isNP0/1005/1.5 pF.

While the invention has been described by way of example and in terms ofpreferred embodiment, it is to be understood that the invention is notlimited thereto. To the contrary, it is intended to cover variousmodifications and similar arrangements (as would be apparent to thoseskilled in the art). Therefore, the scope of the appended claims shouldbe accorded the broadest interpretation so as to encompass all suchmodifications and similar arrangements.

1. A ceramic powder composition, comprising about 80 to about 90 weightpercent of ceramic powders comprising (Sr_(x)Ca_(1-x)Ti) _(y)Zr_(1-y)O₃,wherein x is between 0 and 1, and y is between 0 and 0.1; and about 10to about 20 weight percent of a sintering aid of M^(a) ₂O, M^(b)O, M^(c)₂O₃, M^(d)O₂, or a combination thereof, wherein element M^(a) comprisesLi, Na, K, or a combination thereof, element M^(b) comprises Be, Mg, Ca,Sr, Ba, or a combination thereof, element M^(c) comprises Be Al, Ga, ora combination thereof, and element M^(d) comprises Si, Ge, or acombination thereof.
 2. The composition as claimed in claim 1, furthercomprising an additive comprising oxides of Mn, Mg, or a combinationthereof.
 3. The composition as claimed in claim 2, wherein the contentof the additive is as large as 1.5 weight percent or less.
 4. Thecomposition as claimed in claim 1, wherein y is between 0 and 0.05. 5.The composition as claimed in claim 1, wherein element M^(a) comprisesLi, element M^(b) comprises Ba, element M^(c) comprises B or Al, andelement M^(d) comprises Si.
 6. The composition as claimed in claim 1,wherein element M^(a) comprises one of Li, Na, or K, element M^(b)comprises one of Be, Mg, Ca, Sr, or Ba, element M^(c) comprises two ofB, Al, or Ga, and element M^(d) comprises one of Si or Ge.
 7. Thecomposition as claimed in claim 6, wherein element M^(a) comprises Li,element M^(b) comprises Ba, element M^(c) comprises B and Al, andelement M^(d) comprises Si.
 8. The composition as claimed in claim 1,wherein the sintering aid comprises more than 50 weight percent but lessthan 100 weight percent of M^(d)O₂, 10 weight percent of M^(c) ₂O₃ orless, 10 to 30 weight percent of M^(b)O, and 10 weight percent of M^(a)₂O or less.
 9. A ceramic material comprising a sintered composition asclaimed in claim 1, wherein the sintering temperature thereof is between900 and 1000° C.
 10. The material as claimed in claim 9, wherein theatmosphere during sintering is reductive, and comprises a mixture ofhydrogen and nitrogen.
 11. The material as claimed in claim 1, wherein aratio of sintered density to theoretical density thereof is between 0.9and
 1. 12. A laminated ceramic condenser, comprising: a ceramicdielectric; a plurality of parallel inner electrodes extending in theceramic dielectric; and a pair of outer electrodes exposed on theceramic dielectric and electrically connecting the inner electrodes;wherein the ceramic dielectric comprises a sintered composition,comprising: about 80 to about 90 weight percent of ceramic powderscomprising (Sr_(x)Ca_(1-x))Ti_(y)Zr_(1-y)O₃, wherein x is between 0 and1, and y is between 0 and 0.1; and about 10 to about 20 weight percentof a sintering aid of M^(a) ₂O, M^(b)O, M^(c) ₂O₃, M^(d)O₂, or acombination thereof, wherein element M^(a) comprises Li, Na, K, or acombination thereof, element M^(b) comprises Be, Mg, Ca, Sr, Ba, or acombination thereof, element M^(c) comprises B, Al, Ga, or a combinationthereof, and element M^(d) comprises Si, Ge, or a combination thereof.13. The condenser as claimed in claim 12, further comprising an additivecomprising oxides of Mn, Mg, or a combination thereof.
 14. The condenseras claimed in claim 13, wherein the content of the additive is as largeas 1.5 weight percent or less.
 15. The condenser as claimed in claim 12,wherein y is between 0 and 0.05.
 16. The condenser as claimed in claim12, wherein element M^(a) comprises Li, element M^(b) comprises Ba,element M^(c) comprises B or Al, and element M^(d) comprises Si.
 17. Thecondenser as claimed in claim 12, wherein element M^(a) comprises one ofLi, Na, or K, element M^(b) comprises one of Be, Mg, Ca, Sr, or Ba,element M^(c) comprises two of B, Al, or Ga, and element M^(d) comprisesone of Si or Ge.
 18. The condenser as claimed in claim 17, whereinelement M^(a) comprises Li, element M^(b) comprises Ba, element M^(c)comprises B and Al, and element M^(d) comprises Si.
 19. The condenser asclaimed in claim 12, wherein the sintering aid comprises more than 50weight percent but less than 100 weight percent of M^(d)O₂, 10 weightpercent of M^(c) ₂O₃ or less, 10 to 30 weight percent of M^(b)O, and 10weight percent of M^(a) ₂O or less.
 20. The condenser as claimed inclaim 12, wherein the sintering temperature of the ceramic dielectric isbetween 900 and 1000° C.
 21. The condenser as claimed in claim 12,wherein the atmosphere during sintering of the composition is reductive,and comprises a mixture of hydrogen and nitrogen.
 22. The condenser asclaimed in claim 12, wherein a ratio of sintered density to theoreticaldensity of the ceramic dielectric is between 0.9 and
 1. 23. Thecondenser as claimed in claim 12, wherein the inner electrodes compriseCu.